Question 1116611

Ans:  Width = 7m,  Length = 11m
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The work-out:
LW = 77  (1)
L = 3W-10  (2)

Subs for L from (2) into (1):
(3W-10)*W = 77
3W^2 - 10W - 77 = 0
(3W + 11)(W - 7) = 0  —>  W = -11/3  and/or  W=7 

Discard the negative solution as W>0 is required.

W=7  —>  L=11